\(n_{CaCl_2}=\dfrac{22.2}{111}=0.2\left(mol\right)\)
\(m_{dd_{Na_2SO_3}}=200\cdot1.55=310\left(g\right)\)
\(CaCl_2+Na_2SO_3\rightarrow CaSO_3+2NaCl\)
\(0.2................................0.2.............0.4\)
\(m_{CaSO_3}=0.2\cdot120=24\left(g\right)\)
\(m_{NaCl}=0.4\cdot58.5=23.4\left(g\right)\)
\(m_{\text{dung dịch sau phản ứng}}=22.2+310-24=308.2\left(g\right)\)
\(C\%_{NaCl}=\dfrac{23.4}{308.2}\cdot100\%=7.59\%\)